(1) Field of the Invention
The invention relates to a vibration exciter, in particular for a construction machine, having at least one rotatably supported unbalanced unit with at least one unbalanced element, a rotary drive, a gear arrangement with at least one gear wheel, wherein a rotation generated by the rotary drive can be transmitted by means of the gear arrangement to the at least one unbalanced unit, and a housing, in which the gear arrangement is accommodated.
2) Description of Related Art
A vibration exciter of such type can be taken from EP 0 824 971 B1 for example. Such a vibration exciter, as provided for construction machines, especially for vibrators, has a central rotary drive which sets several unbalanced units into rotation through a toothed wheel arrangement. The unbalanced units each have an unbalanced element which is designed together with the toothed wheels as rotation elements. These are supported on their outside by way of roller bearings in a housing. As a result of the rotating unbalanced masses a selective generation of vibrations is rendered possible. Through an appropriate adjustment of the individual unbalanced units with the unbalanced elements the unbalances can add up or compensate one another.
Vibration exciters of this type are used, for example, in so-called vibrators for driving planks into loose soil.
Furthermore, vibration exciters for generating vibrations can also be employed in drilling devices, as can be gathered from DE 196 08 815 C1 for example. As an alternative or a complement to the rotational movement of a rotary drill drive the vibrations can bring about a significant improvement in the drilling progress.
In the known vibration exciters the unbalanced elements are accommodated together with the gear arrangement in a housing. Due to the fact that the gear wheels and unbalanced masses partially rotate at a high speed of some hundred up to several thousand revolutions per minute, the housing is filled with oil for lubrication.